Measurement of the business benefits of a particular virtualization approach is a function of near-term and long-term predictions.
BY RICHARD BLASCHKE
Few would disagree that virtualization is one of the hottest topics in the storage area network (SAN) space of the IT marketplace. No fewer than 20 vendors have announced storage virtualization products or intentions. Some vendors have "appliance-type" solutions that provide disk pooling, while others have announced approaches based on a SAN operating system or SAN file system.
Much of the discussion to date has been at the technical level, where heated debates center on the merits of "in-band versus out-of-band" and "symmetrical versus asymmetrical"-in other words, where in the network the virtualization intelligence and processing should reside. While these technical issues are scrutinized, little has been mentioned about the business benefits of storage virtualization.
In a broad sense, storage virtualization means storage assets can be aggregated and shared at the block and/or file level. All virtualization schemes involve networks (e.g., Fibre Channel or Ethernet) in which numerous application servers can be connected to multiple storage devices that appear to users as a virtual pool of storage.
Storage virtualization can also provide facilities for the centralized management of storage and enhance flexibility when adding or changing storage capacity. Enabling greater configuration flexibility, storage virtualization can reduce the onerous job of administering environments comprising dissimilar server-attached storage systems, especially when capacity is rapidly increasing beyond their localized physical disk limitations. The network nature of virtualization inherently provides the potential for achieving greater levels of reliability, availability, and scalability through local and remote mirroring, automatic fail-over, LAN-free and server-less backup, and performance optimization.
Whether in-band or out-of-band or hardware or software-oriented, all of the competing implementations of virtualization provide the rudimentary capabilities that every SAN should embrace, including a centrally managed means of sharing storage resources among heterogeneous hosts. However, when evaluating these approaches in the context of solving business-related challenges, decision-makers need to envision how the virtualization architecture will continue to provide value to their organization in the future.
The road to the ultimate storage network can be paved with risk and frustration if the virtualization scheme cannot deliver ever-increasing levels of automation, performance, and return on investment. Tradeoffs that can influence the success of a storage strategy include deploying a solution that was built from the ground up to plug and play in any network versus an appliance-type solution built with off-the-shelf components. The difference is that a "SAN-in-a-box" uses embedded software in a tightly coupled configuration that exploits the feature set and performance of its internal disk drives and network interfaces. A SAN appliance that combines software with a standard platform may serve to disperse the risk and perhaps have initial acquisition cost savings. However, a SAN-in-a-box can alleviate the risk of interoperability and management of multiple devices from multiple vendors. It can also provide better opportunities for scaling capacity and performance as well as seamless integration with applications.
When a solution truly virtualizes storage, rather than merely aggregating disk resources, it can deliver maximum performance and capacity with greater granularity. A virtualization scheme that stripes data across all the physical disk drives to create virtual disks can improve I/O performance because it allows simultaneous access to all drives. This approach also removes the time-consuming effort of managing the physical devices. Virtualization software that uses all of the storage in its domain can provide simplicity, scalability, performance, and low total cost of ownership.
Measuring business benefits
Measurement of the business benefits of a particular virtualization approach is a function of near-term and long-term predictions. Decision-makers need to investigate several aspects of each approach before they can fully understand the business benefits of a particular solution. This investigation should be centered on questions such as:
- If the virtualization solution is used in a very dynamic environment such as e-commerce, will it provide a reduction in total cost of ownership only initially, or also when storage requirements shift or expand greatly over time?
- Will the simplicity of its centralized management scheme endure as the storage network grows in scope, or will it become disproportionately burdensome when there are more nodes or capacity than was anticipated?
- How adaptable will it be to the changing landscape of SAN infrastructure protocols and topologies?
- Will the virtualization scheme be oblivious to spanning geographic distances?
- Will it be able to transition to policy-based management schema with improved levels of automation as capacity and node counts grow?
- How much effort will it take to deploy new applications?
- How can the virtualization scheme be tuned to alleviate bottlenecks and minimize latency?
Business benefits can be mapped from SAN virtualization capabilities in a variety of ways. The most significant impact will be the savings associated with administrative personnel, who can now handle exponentially increasing amounts of storage. Costs of planned and unplanned downtime will diminish substantially, and data protection (backup/restore) and business continuance can improve dramatically. Servers and storage can be added without disrupting the productivity of users or impacting the network. In the bigger picture, storage will take on the qualities of a utility, where storage "power" becomes a commodity, and economies of scale and service-level expectations are easily met.
Achieving the ultimate benefits of storage networking requires an underlying virtualization scheme with enterprise-class features, along with an architectural approach that can meet future requirements. The starting point for most organizations when they are deciding which virtualization scheme to adopt can be determined by the criticality of data storage and how fast and to what degree it will change and evolve in the future. The more substantial the requirements, the more decision-makers need to take a look under the hood to see if the virtualization technology can go the distance. The more that is demanded from storage, the more a tightly coupled virtualization architecture can meet these requirements. This means getting optimal performance from the storage subsystem overall, maximizing the usage of all available disk capacity, providing openness in interfacing to a variety of SAN infrastructures and applications, and having the widest range in scaling performance, availability, and reliability.
Richard Blaschke is the executive vice president of marketing at XIOtech Corp. (www.xiotech.com) in Eden Prairie, MN.